This product is not designed for protection against radioactive rays.
※1 0%, 100% input possible
※2 ILED=VDAC÷RISET×3300
※3 ILED=VISET÷RISET×3300, VDAC＞VISET
● PHYSICAL DIMENSIONS・MARKING
Max 18.85 (include BURR)
Product
series
BD8118FM
Lot No.
HSOP-M28 （UNIT:mm）
REV. A
3/4
●BLOCK DIAGRAM
VREG
LOADSW
VCC
OVP
VREG
UVLO
TSD
OVP
FAIL1
EN
PW M Comp
SYNC
RT
－
＋
＋
Driver
SWOUT
Control
Log ic
CS
OSC
OCP
ERR Amp
COMP
－
－
－
－
＋
－
＋
GND
LED1
SS
Soft
Start
LED2
Current driver
PWM
LED3
LED4
VDAC
ISET
PGND
ISET
Open
Detect
FAIL2
LEDEN1
LEDEN2
●Pin No, Pin Name, Function
Pin
Pin
No
Name
1
2
3
4
5
6
7
8
9
10
11
12
13
14
V
CC
LOADSW
FAIL1
VREG
PWM
SYNC
GND
VDAC
ISET
LEDEN1
LEDEN2
LED1
-
LED2
Power supply
Function
Pin
No
15
16
17
18
19
20
21
22
23
24
25
26
27
28
Pin
Name
LED3
-
LED4
-
-
FAIL2
PGND
CS
SWOUT
EN
OVP
RT
SS
COMP
N.C
Function
LED output （Open Drain）
LED output （Open Drain）
N.C.
N.C.
Fail signal output (Open det : Open Drain）
LED output GND pin
DC/DC output current detection pin
DC/DC SW output pin
Enable pin
OVP pin over voltage detection pin
Frequency set resistor
Softstart pin
Error amp output
FET pin for load sw （Open Drain）
Fail signal output （Open Drain）
Internal voltage regulator
PWM adjustment input
External synchronizing input
Ground pin
DC flexible input
LED output current set resistor
LED output enable pin1
LED output enable pin2
LED output （Open Drain）
N.C.
LED output （Open Drain）
REV. A
4/4
● Operation Notes
(1)
Absolute maximum ratings
Use of the IC in excess of absolute maximum ratings such as the applied voltage or operating temperature range may result in IC damage.
Assumptions should not be made regarding the state of the IC (short mode or open mode) when such damage is suffered.
A physical safety measure such as a fuse should be implemented when use of the IC in a special mode where the absolute maximum
ratings may be exceeded is anticipated.
(2)
Reverse connection of a power supply connector
If the connector of power is wrong connected, it may result in IC breakage. In order to prevent the breakage from the wrong
connection, the diode should be connected between external power and the power terminal of IC as protection solution.
(3)
Power supply and ground lines.
Fluctuating voltage on the power supply and ground lines may damage the device. Be sure to connect a bypass filter capacitor as close
as possible to the IC between the power supply and ground pins. Check that the selected capacitance will not have an adverse influence
on any characteristics, such as a drop in the electrolytic capacitor value that can occur at low temperatures.
(4)
GND potential
Ensure a minimum GND pin potential in all operating conditions.
(5)
Setting of heat
Use a setting of heat that allows for a sufficient margin in light of the power dissipation (Pd) in actual operating conditions.
(6)
Pin short and mistake fitting
Use caution when orienting and positioning the IC for mounting on printed circuit boards.Improper mounting may result in damage to the
IC. Use of the IC in excess of absolute maximum ratings such as the applied voltage or operating temperature range may
result in IC damage.
(7)
Actions in strong magnetic field
Use caution when using the IC in the presence of a strong electromagnetic field as doing so may cause the IC to malfunction.
(8)
Thermal shutdown circuit(TSD)
This IC built-in a Thermal shutdown circuit (TSD circuit). If Chip temperature becomes 175℃(TYP.), make the output an Open
state. Eventually, warmly clearing the circuit is decided by the condition of whether the heat excesses over the assigned limit, resulting
the cutoff of the circuit of IC, and not by the purpose of preventing and ensuring the IC. Therefore, the warm switch-off should not be
applied in the premise of continuous employing and operation after the circuit is switched on.
(9)
Testing on application boards
When testing the IC on an application board, connecting a capacitor to a pin with low impedance subjects the IC to stress.
Always discharge capacitors after each process or step. Ground the IC during assembly steps as an antistatic measure, and use similar
caution when transporting or storing the IC. Always turn the IC's power supply off before connecting it to or removing it from a jig or
fixture during the inspection process
(10)
IC terminal input
This monolithic IC contains P+ isolation and P substrate layers between adjacent elements in order to keep them isolated. P/N junctions are formed
at the intersection of these P layers with the N layers of other elements to create a variety of parasitic elements.
For example, when a resistor and transistor are connected to pins. (See the chart below.)
the P/N junction functions as a parasitic diode when GND > (Pin A) for the resistor or GND > (Pin B) for the transistor (NPN).
Similarly, when GND > (Pin B) for the transistor (NPN), the parasitic diode described above combines with the N layer of other adjacent
elements to operate as a parasitic NPN transistor.
The formation of parasitic elements as a result of the relationships of the potentials of different pins is an inevitable result of the IC's architecture. The
operation of parasitic elements can cause interference with circuit operation as well as IC malfunction and damage. For these reasons, it is necessary
to use caution so that the IC is not used in a way that will trigger the operation of parasitic elements, such as by the application of voltages lower than
the GND (PCB) voltage to input pins.
(Pin A)
(Pin B)
Ｂ
Ｃ
Ｅ
ＧＮＤ
Ｂ
(Pin B)
Ｃ
Ｅ
ＧＮＤ
＋
Ｐ
Ｎ
Ｎ
P Substrate
Ｐ
＋
Ｐ
＋
Ｐ
Ｎ
Ｎ
Ｐ
＋
Ｐ
near by other element
Ｎ
parasitic diode
Parasitic diode
ＧＮＤ
Ｎ
Ｎ
P Substrate
Parasitic diode
Fig of chart of Parasitic diode
ＧＮＤ
(11)
Ground wiring patterns
When using both small signal and large current GND patterns,it is recommended to isolate the two ground patterns,placing a single ground
point at the application's reference point so that the pattern wiring resistance and voltage variations caused by large currents do not
cause variations in the small signal ground voltage. Be careful not to change the GND wiring patterns of any external components.
(12)
LED output terminal
Don’t connect Capacitor to LED output terminal (Pin : 12,14,15,17), as doing so may cause LED short detection to malfunction.
REV. A
Notice
Notes
No copying or reproduction of this document, in part or in whole, is permitted without the
consent of ROHM Co.,Ltd.
The content specified herein is subject to change for improvement without notice.
The content specified herein is for the purpose of introducing ROHM's products (hereinafter
"Products"). If you wish to use any such Product, please be sure to refer to the specifications,
which can be obtained from ROHM upon request.
Examples of application circuits, circuit constants and any other information contained herein
illustrate the standard usage and operations of the Products. The peripheral conditions must
be taken into account when designing circuits for mass production.
Great care was taken in ensuring the accuracy of the information specified in this document.
However, should you incur any damage arising from any inaccuracy or misprint of such
information, ROHM shall bear no responsibility for such damage.
The technical information specified herein is intended only to show the typical functions of and
examples of application circuits for the Products. ROHM does not grant you, explicitly or
implicitly, any license to use or exercise intellectual property or other rights held by ROHM and
other parties. ROHM shall bear no responsibility whatsoever for any dispute arising from the
use of such technical information.
The Products specified in this document are intended to be used with general-use electronic
equipment or devices (such as audio visual equipment, office-automation equipment, commu-
nication devices, electronic appliances and amusement devices).
The Products specified in this document are not designed to be radiation tolerant.
While ROHM always makes efforts to enhance the quality and reliability of its Products, a
Product may fail or malfunction for a variety of reasons.
Please be sure to implement in your equipment using the Products safety measures to guard
against the possibility of physical injury, fire or any other damage caused in the event of the
failure of any Product, such as derating, redundancy, fire control and fail-safe designs. ROHM
shall bear no responsibility whatsoever for your use of any Product outside of the prescribed
scope or not in accordance with the instruction manual.
The Products are not designed or manufactured to be used with any equipment, device or
system which requires an extremely high level of reliability the failure or malfunction of which
may result in a direct threat to human life or create a risk of human injury (such as a medical
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